JSFiddle - React, Tailwind, and code Playground

by Tân Nguyễn

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/rangy/1.3.0/rangy-core.min.js"></script>
<div contenteditable>Hello world!</div>

CSS

div {
  border: 1px solid;
}

JavaScript

var selector = document.querySelector('[contenteditable]');

var setCaretIndex = function (index) {
    var charIndex = 0, stop = {};

    var traverseNodes = function (node) {
        if (node.nodeType === 3) {
            var nextCharIndex = charIndex + node.length;
            if (index >= charIndex && index <= nextCharIndex) {
                rangy.getSelection().collapse(node, index - charIndex);
                throw stop;
            }
            charIndex = nextCharIndex;
        }

        // Count an empty element as a single character. The list below may not be exhaustive.
        else if (node.nodeType === 1 && /^(input|br|img|col|area|link|meta|link|param|base)$/i.test(node.nodeName)) {
            charIndex += 1;
        } else {
            var child = node.firstChild;
            while (child) {
                traverseNodes(child);
                child = child.nextSibling;
            }
        }
    };

    try {
        traverseNodes(selector);
    } catch (ex) {
        if (ex !== stop) throw ex;
    }
};

selector.focus();

setCaretIndex(3);